This invention relates to a method and apparatus for controlling the quantity of water discharged from nozzle devices toward cutting tools during the operation of a drum-cutting mining machine. More particularly, the present invention relates to a method and apparatus for detecting the speed at which a drum-cutting mining machine moves along the face of a mine during the actual mining operation and controlling the quantity of water discharged by the spray nozzles in a proportional relation depending upon the speed at which the mining machine is advanced along the face of the mine.
During the process of releasing rock, especially coal, in an underground mine, it is a common practice to spray the mined rock several times with water from high pressure pipelines in order to prevent the production of excessive quantities of dust. More specifically, in regard to drum-cutting machines, it has become common practice to incorporate such high pressure lines for water in the mining machines themselves and to direct the sprayed jets of water mainly or essentially onto the cutting chisels or bits which are carried on rotatable drums. The supply of a suitable quantity of water to the spray jets naturally depends, to a large extent, upon operating conditions. It is sufficient to spray a smaller amount of water per unit of time if the drum-cutting machine travels in a forward direction at a slow rate and if the amount of rock released per unit of time is relatively small. With faster rates of travel of the drum-cutting machine, it is necessary to spray a larger quantity of water in order to insure that only a relatively small amount of dust is produced.
A valve has heretofore been incorporated in the water supply pipeline of a drum-cutting machine to turn OFF the water supply when the machine stands idle but otherwise the valve remains fully open. As a result, the amount of sprayed water can be excessively large. There may be a critically deficient amount of sprayed water in the event that the mining machine is advanced at a relatively high rate of speed and with a correspondingly large yield of raw ore. The occurring dust will be incompletely washed down due to an insufficient amount of water; while with a lower rate of travel by the mining machine, the raw ore will be excessively wet.